Integrated circuit (IC) devices are used in nearly all areas of modern electronics. As integrated circuit devices become more complex, e.g., including greater numbers of circuits, the need to minimize the size of the integrated circuit device packages becomes increasingly more challenging. One conventional solution to providing increased density with decreased package size has been to stack layers of integrated circuits forming multi-layered or three-dimensional structures. One common application for such a structure is found in conventional memory devices in which two or more layers of memory arrays are fabricated in a stack to form a multi-layered or three-dimensional memory array structure.
Typically, multiple layers in the three-dimensional structure have at least some interconnecting structures to electrically interconnect the individual layers. For example, in the memory array case, the multiple layers of memory arrays are conventionally integrated with controlling circuitry in a base layer of the memory device by forming a plurality of interconnect structures electrically connecting the multiple layers of memory to the controlling circuitry. In another example, conventional integrated circuit layers will typically all require power and ground connections, which can be provided by a single interconnect structure extending through each of the integrated circuit layers.
In order to ensure adequate electrical connection, conventional interconnect structures require a relatively large cross-section which, in turn, requires more lateral space or “real estate” on a semiconductor die. The need for real estate in order to provide such electrical interconnections may reduce the ability to maximize the density of the integrated circuit in order to obtain the greatest functionality in the smallest package size. When the transverse cross-sectional dimension of the electrical interconnections is reduced to make the electrical interconnections smaller, the contact area is also reduced. This decrease in contact area results in an increase in the contact resistance. Thus, the configuration of the interconnect structures for a device incorporating multiple layers or arrays can be a significant consideration in package design to minimize package size, enhance memory density, or both.